Biological Approach Flashcards Preview

What are the two control systems in humans?

Nervous system, endocrine system.

What are the two divisions of the human nervous system? What do they consist of/do?

The central nervous system (CNS) which consists of the brain and spinal chord. The peripheral nervous system (PNS) which consists of millions of neurons that carry messages to and from the CNS.

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What are the 3 neurons in the PNS called?

Motor, sensory, and interconnecting (or relay) neurons.

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What are the two divisions of the PNS?

Autonomic nervous system and the somatic nervous system.

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What are the two divisions of the autonomic nervous system?

Sympathetic nervous system and the parasympathetic nervous system.

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What do motor neurons do?

Carry messages away from the CNS to the organs and muscles.

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What is the structure of a motor neuron?

It has a cell body with many dendrites branching off it. The dendrites have a large surface area. An axon branches off from the cell body, covered in a myelin sheath. Synaptic terminals come from the end of the axon.

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How do motor neurons work?

The dendrites connect with other neurons and carry nerve impulses towards the cell body. The axon carries the nerve impulses away from the cell body.

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What are the cells surrounding the axon?

Schwann cells wrap around to form an insulation layer called the myelin sheath which is white fat.

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What is the gap between neurons called?

A synapse.

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What do sensory neurons do?

Carry messages from the receptors in the body (PSN to the CNS.

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What are some examples of receptors?

Sense organs, muscles, skin and joints.

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What do receptors do?

They detect physical and chemical changes in the body and relay these messages to other interconnecting neurons or motor neurons.

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What is the reflex arc?

A stimulus, such as a hammer hitting a knee, is detected by receptor cells in the PNS which then conveys a message along a sensory neuron. The messages reaches the CNS where it connects with an neuron. This then transfers the messages to a motor neuron, which carries the message to an effector (e.g. muscle) which causes the muscle to contract.

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What are the lengths of the fibres in the three types of neuron?

Motor - short dendrites, long axons.Interconnecting - short dendrites, short/long axons.Sensory - long dendrites, short axons.

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What do synapses do? What is that known as?

Allow electrical messages from one neuron to transfer to an adjacent neuron. It is known as a synaptic transmission

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Explain synaptic transmission.

The nerve impulse arrives at a pre-synaptic terminal. This triggers the release of neurotransmitters which must be taken up immediately by the post-synaptic neuron or it will be reabsorbed by the synaptic terminal or be broken down by enzymes. If transmitted, the impulse is carried along the post-synaptic neuron until it reaches the next synaptic terminal.

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What is a neurotransmitter?

A chemical substance released from a synaptic vesicle that affects the transfer of an impulse to another nerve of muscle.

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What are some examples of neurotransmitters? How can they influence the post-synaptic neuron?

Dopamine, acetylcholine, serotonin. They can act in an inhibitory way (decrease the firing of a cell) or an excitatory way (increase the firing of a cell).

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What is thought to be the cause of schizophrenia in terms of neurotransmitters?

Thought to be the result of excessive activity of the neurotransmitter dopamine. Neurons are too excitatory, and transfer too many messages throughout the brain as a result. When this happens, symptoms of schizophrenia appear.

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How can the symptoms of schizophrenia be controlled?

With anti-psychotic drugs such as chlorpromazine. They block the receptor sites for dopamine.

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Explain the study of Phineas Gage.

Whilst working on a railroad, he was preparing to black a section of rock using explosives to create a new railway line. Gage dropped his tamping iron onto the rock, causing the explosive to ignite. The explosion hurled the metre-length iron pole through Gage's left cheek, passed behind his left eye and exited his skull and brain form the top of his head. The pole was found metres away covered in bits of Gage's brain.

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What was the aftermath of Phineas Gage's accident?

He survived, and after months of rest and recovery looked to get his job back. However no one would employ him due to his personality change from kind and reserved to boisterous, rude and grossly blasphemous.

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What is localisation?

Specific areas of the cerebral cortex are associated with particular physical and psychological functions.

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What is lateralisation?

The dominance of one hemisphere of the brain for particular physical and psychological functions.

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What is a hemisphere?

Hemisphere means 'half'; the brain has a left and right hemisphere.

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What are two scientists that were involved in the research of localisation of cortical function?

Paul Broca and Karl Wernicke.

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What can hemisphere's control?

Speech and language.

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What are the three concentric layers of the brain and what do they do?

Where is the motor area located and what does it do?

In the parietal lobe. It is responsible for controlling voluntary movement. Movements on the right side of the body are controlled by the left hemisphere and vice versa.

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Where is the somatosensory area located and what does it do?

In the parietal love, separated from the motor area by the central sulcus. It responds to heat, cold, touch, pain and our sense of body movement.

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What is the amount of somatosensory area associated with a particular part of the body related to?

Its use and sensitivity - e.g. rats whiskers have a separate cortical area. Human hands and face talk up more than half.

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How do the eyes connect to the occipital lobe? Therefore, what does damage of one hemisphere result in?

Nerve fibres from the inner half of the retina cross at the optic chiasm and travel to opposite sides of the brain. Damage to the left hemisphere can result in a loss of vision in the right eye.

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What is the optic chiasm?

The point at which the nerve fibres from both eyes converge.

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Where is the auditory area located? What is it responsible for?

In the temporal lobe. It analyses speech-based information.

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What is the Wernicke's area and where is it?

Found in the left temporal lobe, it is responsible for comprehension of speech. Damage causes Wernicke's aphasia - speech is rapid and disorganised (no grammatical sense).

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What is a split-brain patient? What were they being treated for?

They have undergone a corpus callosotomy where a large part of the corpus callosum is lesioned (cut). This was a treatment for severe forms of epilepsy.

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What is the result of split-brain surgery?

The two hemispheres of the brain cannot communicate as effectively.

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What research was done on split-brain patients?

Roget Sperry and Michael Gazzaniga tested various cognitive and perceptual processes. They administered tasks known to be associated with each hemisphere of the brain to the patients. They discovered that the two halves of the brain were able to function independently.

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What does the CNS control?

All life functions and psychological processes.

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What does the somatic nervous system control?

Senses and sends instructions to muscles.

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What does the autonomic system control?

Bodily organs (hormonal). Most are not under conscious control - heart, stomach.

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What is Broca's area of the brain?

It is found in the left frontal lobe and is responsible for the function (generation) of speech. Damage causes Broca's aphasia which makes speech slow and laborious.

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What was the earliest method for studying the brain?

Phrenology, where you feel for bumps on the head of a patient and attribute it to behavioural characteristics.

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What are the two blanket categories for studying cortical specialisation?

Invasive and non-invasive.

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What are the two invasive methods of study?

Neurosurgery and electrical and chemical stimulation.

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What is neurosurgery?

Manipulating structures within the brain using either ablations or lesions.

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What are the experiments using neurosurgery?

David Hubel and Torsten Wiesel looked at sensory processing. They inserted a microelectrode into the visual cortex of an anaesthetised cat. They then projected patterns of dark and light onto a screen in front of it, and found that some neurons fired quickly when the lines were presented at certain angles. These neurons were called simple cells. Some responded best to lines of a certain angle that move in one directions and are called complex cells.

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What is electrical and chemical stimulation?

Using electrodes and chemicals placed into specific areas of the brain to see how it is affected.

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What was the electrical stimulation experiment?

They were testing the effects of reticular formation in rats when they accidentally placed an electrode in the septal area. This part of the limbic system was associated with pleasure, and when the rats learned they could control the stimulation would press the lever repeatedly.

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What is ablation?

A surgical procedure used to remove areas of the brain.

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What is lesioning?

A surgical procedure used to cut neural connections in the brain.

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What is reticular formation?

A complex network of fibres, extending from the core of the brainstem to the thalamus, involved in maintaining functions vital to life.

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What is the Wada test?

Also known as the intracarotid sodium amobarbital procedure (ISAP), it is a chemical test used to establish which cortical functions are located to which hemisphere.

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When is the Wada test used?

On patients prior to surgery to establish which side of the brain is responsible for speech and memory so that damage to these structures can be minimised during surgery.

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How is the Wada test carried out?

The patient is kept awake and an anaesthetic is injected into one hemisphere at a time to 'shut down' memory and language functions in that hemisphere so an evaluation can be made of the other hemisphere. Recovery from anaesthesia is quite rapid and an EEG is used to record when the medication has worn off.

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What is a post-mortem study?

A patient, who has usually been the subject of a longitudinal study due to a rare affliction, is studied after death. The area of the brain that is damaged is attributed to the affliction suffered.

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What did Paul Broca study using post-mortems? Describe one of his patients.

The location of speech production in the brain. One of his first patients was nicknamed Tan due to his inability to say any words clearly other than tan. Through an autopsy, Broca found that Tan had a lesion in the left cerebral hemisphere caused by syphilis. This area became known as Broca's area, and damage can lead to Broca's aphasia.

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What are the four non-invasive methods of study? Which one isn't a scan?

How are EEGs carried out?

It is a measurement of electrical activity in the brain by recording electrodes placed on the individual's scalp. The voltage differences between different parts of the brain are recorded, and the signal is displayed on a screen. This help clinicians monitor situations.

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What has EEG contributed to?

Theories of sleep behaviour.

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What is a CAT scan?

A narrow X-ray beam is sent through the patients head and the amount of radiation absorbed is measured. The measurements are fed into a computer which gives a cross-section of the brain.

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What is a PET scan?

Different levels of neural activity, in various locations, are assessed whilst the brain is still active. A small amount of radioactive glucose is injected into the bloodstream, and after a few minutes the brain begins to use it.

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What is an MRI scan?

Scanner use strong magnetic fields and radio waves to produce a high quality image of a persons brain. The patient lies in a tunnel surrounded by a large magnet which produces the magnetic field. When a certain area of the body is exposed to a radio-frequency pulse the tissues give out a signal which is measured.

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What can CAT scans be used for?

Swelling due to tissue damage and the size of the ventricles can be evaluated. It can also detect tumours.

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What are PET scans used for?

The PET scan detects and measures the amount of radioactivity emitted when individuals perform tasks.

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What are MRI scans used for?

Diagnosing diseases of the brain and spinal chord such as multiple sclerosis, which can't be detected with a CAT scan.

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What are the strengths and limitations of neurosurgery?

Strength - Allows for specificity and control in the location of damage.Limitation - Cause and effect. Does lesioning one area cause damage to other areas?

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What are the strengths and limitations of electrical and chemical stimulation?

Strength - Less harmful than surgery and more ethical.Limitation - Problems with extrapolating research conducted on animals to explaining human cortical function.

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What are the strengths and limitations of post-mortem studies?

Strength - Greater understanding or rare afflictions in individuals.Strength - Ethical. The person is dead so there will be no damage.Limitation - Obtaining a person's brain can be difficult

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What are the strengths and limitations of EEG?

Strength - No intervention is necessary and therefore allows for natural measurements of brain activity.Limitation - Electrodes are not sensitive enough o pick out individual action potentials of single neurons.Limitation - Not as accurate as scans.

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What are the strengths and limitations of scans?

Strength - Provides detailed knowledge of areas of the brain that are active whilst completing tasks.Limitation - Some scans are time-consuming so cannot record spontaneous behaviour.Limitation - Ethical issues with the injection of radioactive glucose (PET scans).

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What is the problem with using animals in experiments?

It is difficult to generalise to humans.

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What is an issue with post-mortem studies to do with the patients family?

They might be distressed by the idea, or not consent to it happening.

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What does the somatic nervous system control?

Skeletal muscles and it receives information to and from sensory receptors.

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What does the autonomic nervous system do? How does it operate?

Maintains homeostasis by controlling glands and vital muscles. The system operates involuntarily.

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How are the actions of the sympathetic and parasympathetic nervous system described?

Antagonistic - they work in opposition to each other.

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What are the sympathetic and parasympathetic nervous systems described as? Give an example.

Sympathetic - fight or flight system.Parasympathetic - rest and digest system.Sympathetic would speed up the heart rate, parasympathetic would slow it down.

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How does the fight or flight response work?

Your body diverts blood away from you stomach to your muscles so that you can stay and fight, or run away. Your heart rate increases along with other sympathetic responses. When the threat has subsided the parasympathetic nervous system restores your body to its normal state. You may still be shaking as hormones in the bloodstream take longer to disperse.

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What is the endocrine system?

It is composed of a number of glands that release hormones directly into the bloodstream. It acts slowly to transport these hormones around the body.

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What is a major gland in the endocrine system and what does it do?

The pituitary gland, also known as the master gland, controls the release of hormones from all other endocrine glands in the body.

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What happens in the endocrine system during a threatening situation?

The pituitary gland releases ACTH which is the body's major stress hormone. It is then carried around the bloodstream and stimulates the adrenal glands to release adrenaline directly into the bloodstream.

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What does prolonged exposure to stress hormones do?

It can be damaging physically and psychologically. Effects include disruption to sex life, digestion problems, and in severe cases heart disease.

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What contradicts the involuntary nature of the autonomic nervous system?

Zen Buddhists are able to control a number of functions whilst meditating such as heart rate and oxygen consumption. They are therefore able to control any potential negative effects of stress.

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What is a genotype?

The genetic make-up of an individual.

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What is a phenotype?

The characteristics shown by an individual that are a results of both genes and the environment.

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What does heterozygous mean?

The genotype consists of two different genes. For example, Bb.

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What does homozygous mean?

The genotype consists of two genes that are the same. For example, BB.

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What would happen if identical twins were raised in different environments?

One twin may show a completely different phenotype to the other twin. For example, different diets could cause difference in strength and height.

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What is one disorder that can be used to explain the difference between genotype and phenotype? (enzyme deficiency)

Phenylketonuria (PKU) is characterised by a deficiency in the enzyme PAH. It is a recessive genetic disorder. Of undetected and untreated, the child can fail to accomplish important developmental milestones. However is PKU is diagnosed early a new-born can develop normally when given a special diet for the rest of their life.

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What is one disorder that can be used to explain the difference between genotype and phenotype? (blood coagulation)

Haemophilia is a recessive genetic illness that impairs the body's ability to control blood coagulation. It is more common in females.

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What are monozygotic (MZ) twins commonly referred to as?

Identical twins.

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When do MZ twins occur?

When a single egg is fertilised to form one zygote, but divides to form two separate embryos. They develop into two foetuses while sharing the mothers womb. This usually happens after two days, resulting in shared placenta and two separate amniotic sacs.

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How often to conjoined twins occur? How is it thought to happen?

1 in 50,000. They are physically united in some way, due to the zygote dividing too late - around 13 days after fertilisation.

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What is a zygote?

A fertilised cell (union of egg and sperm cell).

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What does dizygotic mean?

Two zygotes. These twins are formed when two separate eggs both become fertilised by different sperm cells.

Why do psychologists study MZ and DZ twins?

To investigate the genetic basis of behaviour.

What does concordance mean?

Agreement between; the extent to which a pair of twins share similar traits or characteristics.

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What is meta-analysis?

Statistical analysis of the results of a number of the same or similar studies.

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How do twin studies work in separating environmental and biological factors?

In MZ twins, there should be a 100% concordance if biology is the cause. If environment is the cause, when raised apart, the concordance should be lower.

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What was the twin study on intelligence?

Wilson conducted a longitudinal study and found that at the age of 18 months, MZ twins were more similar than DZ twins on tests of infant intelligence. The follow-up data over the next 13 years showed the MZ twins were more similar than DZ twins in their intellectual performance.

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How can the intellectual difference in DZ twins be accounted for?

The difference in genotypes may have directed them along separate developmental paths would account for their 'poorer' intelligence.

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Who conducted a meta-analysis on twins? What of?

Bouchard and McGue studied the degree to which IQ scores are inherited.

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What is the evidence for homosexuality being biologically determined?

Bailey and Pillard found in a study of male twins where at least one pair was gay, that 52% of MZ brothers were concordant for homosexuality and 22% for DZ twins. Another study found a 30% concordance in MZ twins on the Australian registry.

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What is the family study on addiction?

Sons of alcoholic fathers were more likely to be alcoholics themselves, compared to random people. When sons of alcoholics drank alcohol. they tended to release more of the neurotransmitter endorphin, suggesting a biological predisposition to alcoholism.

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What is the evidence that suggests the environment plays a more significant role than genes?

When researching IQ data of 40,000 Dutch males born in 1944, they found that IQ is related to birth order and family size. This is due largely to the degree of attention given by parents.

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What is the adoption study into age and ability?

As children grow older it is assumed that their cognitive and verbal abilities would be more like their adoptive parents. However, as they approached the age of 16 they became more similar to their biological parents suggesting a genetic influence.

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What is the adoption study into intelligence?

Black children from low socio-economic backgrounds that were adopted into white middle-class families, where the adoptive parents had at least one biological child. The black children were found to be more similar to their biological parents than their adoptive parents supporting a genetic basis for intelligence. However inter-racial siblings showed some intellectual similarities suggesting an environmental influence.

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How does selective breeding show whether it is a product of environment or biology?

If selective breeding does not alter the trait or characteristic, then we must assume that the it is entirely dependant on environmental factors.

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What are examples of genetic basis for behaviour?

Fruit flies - bred to be more or less sensitive to light.Mice - dependant on alcohol.Dogs - excitable or lethargic.Chickens - aggressive and sexually active.

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What was the study by Tryon?

He trained a large number of rats to run a complex maze. The rats that were the quickest were selected as well as the slowest. They were then bred to be 'bright' and 'dull' rats, and continued this for generations. Maze bright rats learned to run the maze faster and made fewer errors compared to maze dull rats. This shows learning is a heritable, genetic characteristic which can be controlled through selective breeding.

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Why can't Tryon's study be generalised easily?

Humans interact very differently in their environment to rats.

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What was the study similar to Tryon?

They bred maze dull rats in one of two environments;-impoverished or boring, consisting of a barren wire-meshed cage.-stimulating containing tunnels and ramps.

When the rats reached maturity, the ones raised in a stimulating environment made the same number of errors as maze bright rats in a stimulating environment. This shows environment is also an important factor in determining behaviour.